1. Field of Invention
The present invention relates to a fan and a motor thereof. In particularly, the present invention relates to a fan and a motor thereof configured with a magnetic element for magnetically attaching to the shaft so as to stable the rotation of the shaft.
2. Related Art
FIG. 1A is a schematic diagram showing a conventional fan 1A and its motor 10. The fan 1A includes a motor 10 and an impeller 40. The motor 10 connects to the impeller 40 for driving it to rotate. The impeller 40 has a hub 41 and a plurality of blades 42. The motor 10 has a rotor 11, a stator 12 and a frame 13. The rotor 11 is connected to the stator 12 through a connecting ring 14. The centers of the magnet 111 of the rotor 11 and the coil 121 of the stator 12 are located at the same level. In other words, the magnetic center A of the magnet 111 and the magnetic center B of the coil 121 are located on the same horizontal plane. Accordingly, when the rotor 11 is rotated, the airflow passing through the rotor 11 applies a reacting force to the rotor 11, so that the rotor 11 vibrates vertically. Accordingly, the shaft 112 of the rotor 11 is moved vertically. This may cause the noise of the fan 1A in the operation, and the abrasion of the connecting ring 14 or other components, thereby shortening the lifetime of the motor 10.
In order to decrease the noise and the abrasion, another fan 1B is disclosed. As shown in FIG. 1B, in the fan 1B, the magnetic center A of the magnet 111 is slightly higher than the magnetic center B of the coil 121. In other words, the center of the magnet 111 is higher than that of the coil 121, so that a vertical gap is formed between the magnetic centers of the magnet 111 and the coil 121. Accordingly, when the rotor 11 is rotated, the magnetic field provided by the coil 121 can not only drive the rotor 11 to rotate, but also apply a force to pull the rotor 11 downwardly, which can eliminate the reacting force that pushes the rotor 11 upwardly.
However, the motor of the fan may be operated in different rotation speeds and environments. For example, the motor may be operated in high rotation speed or upside down. If the motor is upside down, the misaligned configuration for the fan 1B can not provide proper force to pull the rotor 11, which sufficiently restricts the application of the fan 1B. Besides, since some energy is transformed to the reacting force for pushing the rotor 11 upwardly, the rotation speed of the fan 1B can not be efficiently increased.
Therefore, it is an important subject of the invention to provide a fan and a motor thereof that can reduce the noise and vibration so as to decrease the abrasion of the components and improve the application.